Electrothermal Atomic Absorption Spectrometric Determination of Copper(II) Using a Tungsten Metal Furnace after Preconcentration onto Chitosan

Abstract

The properties of chitosan to adsorb metal ions and to dissolve in some organic acids were applied to the preconcentration and determination of copper(II) in water samples by tungsten metal furnace atomic absorption spectrometry. Copper(II) was quantitatively adsorbed onto chitosan over the pH range of 5.0 - 9.0. The chitosan adsorbed copper(II) was separated from the sample solution by a membrane filter, then dissolved in 2.0 cm³ of 0.1 mol dm^-3 acetic acid. An aliquot of this resulting solution was introduced directly into a tungsten metal furnace, and the absorbance of copper was measured by atomic absorption spectrometry. An ashing temperature of 900°C and an atomizing temperature of 2500°C were selected, respectively. The detection limit for copper(II) was 0.002 µg dm^-3 (S/N≥3). A quantitative recovery was obtained over the 50 - 500 dm^-3 range of the sample solution. The relative standard deviations (n=5) were 3.8% for 0.10 µg Cu(II)/100 cm³, 4.7% for 0.05 µg Cu(II)/100 cm³. The proposed method was applied to the determination of trace amounts of copper(II) in water samples.